Automatic telephone-exchange.



PATENTED JUNE 25, 1907.

N. E. NORSTROM. AUTOMATIU T'ELEPHONE EXCHANGE.

APPLIOATION FILED MAY 31,1 0.

90 12 SEEETB-SHEET 1.

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. N. E. NORSTROM. w

. AUTOMATIC TELEPHONE EXCHANGE.

APPLICATION FILED MAY 31, 1900.

12 SH HEB! 2.

PATENTIED JUNE 25, 19,07.

N. E. NORSTROM. I AUTOMATIC TELEPHONE EXCHANGE.

12 SHEETS-SHEET 3.

APPLICATION-FILED MAY 31,1900.

PATENTED JUNE 25, 1907. EQNORSTROM. v

' AUTOMATIC TELEPHONE EXCHANGE;

APPLICATION FILED MAY 31, 1900.

12 BHEETSfiBHEET 6.

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PATENTED JUNE 25, 1907. I N. E. NORSTROM. AUTOMATIC TELEPHONE EXCHANGE.

APPLICATION FILED MAY 31,1900.

I 12 SHEETS-SHEET 6.

' PATENTBD. JUNE 25,1907. 1N.\E.N0RSTR0M. AUTOMATIC TELERHONE EXCHANGE.

APPLIUATION FILED MAY oo.'

12 SHEETS-SHEET 1.

9 V aoooeooooooo 4 oooooeeoooooooooooooooo v m K .NO. 857,959. PATENTED JUNE 25, 1907.

N.- E. NORSTROM. v AUTOMATIC TELEPHONE EXUHANGE.

APPLIUATION FILED MAY 31, 1900 12 SHEETS-SHEET B.

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.No. 357,959. PATE-NTBD JUNE 25, 1907.

' N. E. NORSTROM.

AUTOMATIC TELEPHONE EXCHANGE.

PPLIOATION FILED MAY 31,1900. 1 A 12 SHEETS-SHEET 10.

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UNITED STATES PATENT OFFICE.

'NILS' 'EMEL "'NORSTROM, .OFJUNCTION ol'rr, KANSAS, ASSIGNOR OF ONE- HALF TO JOHN ANDERSON, OF SALINA, KANSAS, AND ONE-SIXTH TO E. RICHARDSON, F STERLING, KANSAS.

'AUTQMA'TIC .TELEIPHONE-EXCH'ANGEL No. some.

rammed June 25, 1907.

Application filed May 31, 1900. Serial No. 18,519.

To allwhom it mayv concern.-

Be it known that I, NILB EMEL NORSTROM,

a citizen of the United-States of America, and

I a resident of Junction City, county of Geary, ,5 and State of Kansas, have invented certain new and usefullmprovements in Automatic Telephone-Exchanges, of which the following i is a specification.

My. mvention relates to automatic telephone exchanges and has for its object the construction and arrangement of devices which will simplify the process of selection; and another object of which is arrangements and construction which-willreduce the cost I 5 'ofinstallation and secure perfection of operawill indicate .whether the fault lies with the subscriber' or the apparatus. By theman- 301161 in which I control the operation of the switches at thecentral ofiice, it is not neces-' sary for me .to use three wires between the local station and the central office, for the purpose of securing completeemetallic connections betweentwo su scribers, nor is it necessary for meto use copper wires, .as'is ordinarily the case.

' In the accompanying drawings, Figure 1 is a front elevation of 'one of the switch mechan- 0 isms located at the central ofiice;'Fig- 2 is a side elevation of the same Fig.;3 .isa section on line 33 of Fig. 1, part of the'section being'ofiset so as to-showthe insulation of one ofthe guide-rods; Fig. 4 is a transverse section on line 44 of Fig. 3; Fig. 5 is a partial section on line 55 of Fig. 3; Fig. '6 is a front elevation of one of the telephone-boxes at a local station; Fig. 7 is a similarview with the front cover of the box removedifFig. 8 is thereto.

.wirel B will be drawn by spring section showing some of the arts .in the lower part of the telephone box; Flg. 12 is a detail of some of the gears connected with the generator shown in Fig. 9; Fig. 13 is a section on line -1313 or Fig. 8; Figs. 14,15 and 16, taken together. are a general diagram, illustrating three switch mechanisms at the central office,- together with three telephones connected In the said drawings, R represents the framework on which'is supported a block of insulating material R in which are a series of contact points T, arranged in'double rows as shown'in Fig. 1, and also in the diagrams.

. Secured to the side of the frame R are two side-plates R which support some of the oplever A of which, there is a pawl A arran ed to engage a ratchetwheel F on the sha t F. The pawl 'F serves .to prevent a backward movement of-the shaftjF. Also secured on the same side-plateis a ma net eratingmechanism. Secured to the right-hand I side plate R is a magnet A, on the armature B whose armature lever B carries a paw B ada ted to engage a ratchet wheel E} on the s'ha t E. The holdin pawl E prevents. a

return movement of t e shaft E until said pawl has been released. On the pawl B is a cut in B which is engaged by a pivoted .wire as shown in Figs. 1 and 2. 'On the armature lever A is a rod or arm A which projects outward and engages the extreme end of a wire B so. that 'when'the magnet A is operated, the rod A will push the pawl B hold the pawl B out o engagement with the ratchet wheel E. It will therefore be evident that'if the magnet A is operated, and immediately thereafter the. magnet B be operated, the last 0 eration will not rotate t e ratchet wheel 3. The amount that pawl B is pushed downward out of engagement with the ratchet wheel E is suflicient so thatwhen the magnet B is operated, he

V and by t.

pawl B will pass under the stop E and engagethe "re E connected to the pawl E in engagement will push the pawl E away 'irom and. release the ratcluitwhcel. E When so released, the shaft it will be rotated. backward to its normalposition by a spring E, shown in Fig. 1, adjacent to which spring is a disk E to hold the spring from This insulation is shown at H and the insulations' are so arranged that each alternate rod is in electrical connection with the bar H, and the other rods are in electrical connection with the bar H. Supported l etween each pair of bars .11 is a sliding block ll which is divided into two parts insulated from each Between other, as shown in Figs. 1 and 5. the two parts ol one of the sliding blocks II is a bracket or lug which extends outward and has pivoted to it a-rack lliwhich extends upward parallel to the rods 11 or nearly so. Supported in the side frames R is a shaftJ,

on'whichare a series oi blocks J. which serve as guides for the upper ends. of the racks II. On the shaft F are a series of gears F winch are arranged to engage the series ofracks H.

On each rack 1-17, at a point nearits pivot H is a weight H which acts to hold theracks- H normally out of engagement with their gear wheels F. On the shaft E are a series of arms E arranged in line with the racks I-I and also arranged with one in advance of another,s0 that the series of them takes the form of an open fan, as shown in Fig. 3. The armsdi are arranged. s9 that when the shaft E is rotated, they engage, one at a time, with the racks H and pushthem into engagement with their gears F., These parts are so ar rangedthat by operating the magnet B,

eachtOoth-o-fi the ratchet wheel IE will move an arm into engagement with a rack II, and bring said. rack into engagement with its proper gear. As the ,ratchet. wheel E is moved forward step"'by ste succeeding armsE move succeeding racxs H into engagement with their respective gears. By

this means the operation of. the magnet B selects any desired one of a number of such racks .H" by bringing it into engagement w th a gear so that it will be moved. upward when the shaft F is rotated. Secured on the rear faces of the sliding blocks H are two'con tact; makers P and P Each contact maker is in electrical connection withthe part of the sliding block H, to which it is attached, and is insulated from the. other half; As the aces of a block ll" are in electrical connection with the guide rods 11 on which they are required pair of contact points guided, and as these rods are in electrical connection with the supporting cross-bars ll and ll, it. will therefore be apparent that the contact makers l and P are respectively in electrical connection with the cross-bars ii and ill. in the diagram, contact makers in electrical connection with the cross-bar ll have been marked P, and those in electrical connection with the cross-bar l l have been markedP'. .These contact makers P and P are arranged so that when the connected rack is moved. upward step by step by operation ol the magnet A, saidcontact makerswill engage successive pairs of contact points T.

it will be apparent from the description so far given that by operating magnet B, any desired pair of contact makers P and P may be selected and that by operating magnet A the selected contact maker's may be moved upward any required distance to select any in the corresponding vertical row of contact points. It

will also be apparent that after having. operv ated magnet .13 and then magnet A, it magnet B be again operated thepawl B will release the pawl E so that the shalt E willbe re turned to its normal position by the spring E. This return of the shajlt E moves the engaging arm E away from the engager'l rack H, when the weight H tipsthe moved rack out 1 ward from engagement with its gear F when said rack will liall by gravity to 'itsliorinal position, which normal position is determined by a series of set screws 11?, against. which. the blocks H rest in their lowest position.

On the front cover of the telephone box is arranged a slide M which is vertically novable in guides M In the said slide are a. series of small holes M which are innnbered consecutively fronrl to any required 'nuinbcr, according to the length the slide M, which length is determinedby the number of holes required. On the lower front portion of the slide Mis a projection V by which the vertical position of the slide M may be adjusted by hand. Adjacent to the projection or lug V isa pointer V", and on the front face of the outer guides M are a series of graduations'marked from 0 to 9, as illustra ed in the lower right-hand portion of Fig At its lowest or normal position, the pointer or indicatdrV points at the graduation'niark'ed 9. Inside of the trlephonebox is theordinary ge'nerator G, which may be rotated in the ordinary manner by crank G on'the front of thetelephone box. On the crank shaft of the said generatoris a small gear G which is engaged by a segment of" a larger gear G,

pivoted [to a bracket on the generator G.

Secured on a hub ofthegear G isa'ratchet wheel G and loosely supported on said hub, between the gear G" and ratchet G, a large gear G which engages a gear U on the armature of saidgcnerator. Pivoted on'the gear G is a pawl G arranged to engage with the turned clock-wise, the ratchet wheel G is G is sufiicient to cause it to do so.

tation of NH- g'ear G and consequently of the 'the crank is turned in an opposite direction,

Cr, and as a censequence the armature of the Secured on the rear face of the disk-4'6 is an portion of the rotation of the armature of the ratchet G so that when said ratchet is turned 1n one dircctionfsaid turni'l'lg will cause a 'roarmature ol the generator.' When, however,

generator will not be rotated. On the armature shaft is a segment of a disk 46 on Whichthere is a pin G", to which is connected vaspring G tending to hold the armature of said generator in a given position. When the crank G is rotated clock-wise,.the ratchet wheel G dr'ives the gear G which in turn drives the gear G and consequentlythe armature of the generator. If, however, the speed of rotation is not sufficient to generate a current, the tension of the spring(} will accelerate the movement ofthe armature during the last half of the. rotationto a speed suflicient to cause a proper current to be generated. This acceleration is permitted by reason of the fact that when the-cranki's driven as fast as the crank, but thegear Gr may move faster by the pawl G riding over the ratchet wheel if the tension of the spring If, however, the rotation of the crank G by hand is of speed sufficient to cause a proper generation of a current, the spring G10 does not act to accelerate the speed of the armaturer The spring G therefore-acts to stop the armature at a given position, when the crank is not being rotated, and also to produce a certain required speed of the a'rn'iature of the generator at a certain required portion of its rotation.

with the spring 7 O and permits it to'break its% electrical connection with the spring 69? sulatingly secured to the generatori'rame isa l contact spring 45, which is engaged by disk 46 at one portion of its rotation so as to make electrical connection between the two at that particulartime, but to break such electrical connection at other portions of the'rotation. Pivoted on the front cover is a bell crank lever M, which is engaged by pin G at one generator. This engagement causes a vibration of the bell crank lever M on its pivot. Secured at asuitable point on the cover of, the telephone box is a lever M which carries a pawl M ada ted to engage a ratchet bar M secured on sli e M. The lever Miis connect. ed by a 1nd M to the bell crank lever M so that when the lever M is engaged by pin G, the vibration of thelever M will cause the.

same vibration of the lever M the result of which is to cause the pawl M to-engage the and consequently ,the connected slide'M,

'from-a downward movement until the said pawl 'M" is released as will hereinafter be described- On the pawl M is a bent wire M, which enga es a post M in such a manner that when file lever M is at its normal position, as shown in Fig. 8, the pawl 1W is en agement with the ratchet M. he receiver ho k K is secured to a shaft K, on which shaft is also secured an arm K oneend of which carries a pin Secured on a block at; the side of the telephone box, and in the 'path of the in K is a bell crank lever 66, they hori zonta arm of which is flexible, and the outer end of which has a curved lip of thesame character as that illustrated in another similar piece in Fig. 13. This horizontalarm is so arranged that when the receiver is hung upon the hook K, the pin K .will engage the upper edge of the horizontal on the armature of which isan arm Q adapted to ven age the end of a catch Q that enout ofgages an holds the bell crank arm 66 in the position shown in Fig. 7 Adjacent to the arm 66 is a contact point 67. These parts are so arranged that upon the operation of the bell ringer Q,-.the arm Q will strike the catch Q releasi it from the arm 66, when said arm will be orced, bythe spring, backinto contact with the contact point 67. lf,after {this operation has taken place, the receiver .be

hung u'pon the receiverhookK, the pin K will engage the upper portion of the horizon tal arm'of 66,,pressing it downward and thus pressing the vertical arm back so it will again ecaught by the catch Q and be held away frem the contactpoint 67. On the other end of the arm K are supported an insulated contact spring 76 and another contact s ring 74, whichis in electrical connection wit 1 they arm K and consequently with the shaft K "and the receiver hook Adjacent to, and .in the path of thecontact springs 74:- and 76-, is a strip 73, having contact points 73 and 73- at its twoends, as shown in Fig.7. Midway between the two contact points on the metallic strip. 73 is an insulated contact point 77. In Fig. 7 the hook K and the con- .tact springs 74 and 76 are shown in their mid ositlon. When the receiver 18 on the hook ,,'the contact spring 74 is in the position in which 76. is shown, and 76 is in a position above the contact point on the upper end of When the receiver is removed from the hook K, the contact spring 76 is in the position of contact spring 74,- as shown in Fig.

7, and the contact spring 7 4 is below the contact point on the lower end of 7 3'. lt will therefore be evident that, in the movement of the receiver hook from the upper extreme to the lower, the contact spring 76 will en gagethe contact point-'77, and at the same moment the contact spring 74 will engage the lower contact point on the strip 73; 3 in the assing dowl'iw'ard of the receiver endof the look K, these springs'will'pass upward over thesepoints, then pass out of connection I with them into the position shown in Fig. 7,

and following this t 1e contactspring 74:will

engage the contact point 77, while at the same time the contact spring 76 will engage the upper contact point on the strip 73, after which, further movement will cause these strips to pass out ofengagement with the said contact points. Also located on the shaft K is another metallic piece K having tWo arms nearly horizontal, and the third arm'K projecting upward. Oneof the horizontal arms of K is connected by G to an arm of the gear segment G so that when the receiveris placed 11 on the receiverhook K, the

saidsegment wil be moved soas to turn-the ;ear Gr and consequently the ratchet'wheel G and the gear G there'sult of whichis to give the armature of the generatorG; two rota- 'tions. r'easonof removing the receiver, the segment G rotates the gear Gt and ratchet wheel'G in theop osite direction, in which case the ratchet w eel moves under the pawl .G arfd the armature isnot'rdt'at L It jll fl -v fore be apparent that'when the receiver is placed upon the hook K, the result is to give the generator two rotations, making two electrical connections between 46 and 45 while on theother hand, the rising of the. hook K, due to the removing of the receiver; does not'iin' any way affect the armature of the generator. ThesegmentGr is so related to movement that when the receiver hook K is at its lowest or at'its highest position, the

1 said segment is free from the gear G and consequently, the said gear and the armature of the generator may be rotated wlthout 1ntion.

tcrfering with the se'gment G or the hook K.

Theother horizontal arm of'the metallic piece K is-provide'd' with a rod M which passes through a'tail-piece on the holding On the rodM" is an adjusting nutpawl M".

1 which may be set at any required posi- These parts are so arranged that upon the descent of the hook K, by reasorvof the receiver being placed upon it, the rod M will descend so that the nut thereon will engage the tail-piece on the pawl M, thereby releasing said pawl 'l-romthe rack M" so that said rack, and the shdcM to which 1t is connected,

may fall by gravity to its n'ormalposition." Located on the cover of the; telephone box,

near its upper p'ort1on,*1s a bell crank lever 43, the horizontal arm of which is flexible and lies in the i Secured When the receiver hook K rises, by

reaches outward intothe path of the holes M in slide M. The end of the l'iorizontal arm of the hell crank 43 is-provided with a a lip W, which isigiven a curve, as shownin Fig. 13; The other end'oi the'bell crank 43 is arranged so as to engage either of two con- -.tact points 42 and 57 which are secured to the cover of the telephone box. On the lower end of the hell crank 43 is a in K that pathof the arm K on t is metallic piece K box are two brackets V in which is su ported a vertical shaft or rod'V; Loose y mounted on the shaft V is an arm 'V-, the free end of which constitutes a pin adapted .to be inserted into any one of the series of ear one corner'of the telephone holes M in the slide M; When the pin is thus inserted into one of the holes NP, it projec-ts through so that when the slide M, is, moved upward, thesaid' pin will engage the lower-part of -the horizontal arm of the bell crank 43, moving it upward and-shifting the other arm from the contact point 42 to con tact'point 57. hen the receiver is placed" on the hook K, the movement of the arm K engages the pin K on the bell crank 43 and moves the said bell crank'from contact point.-

57' to the contact oint 42. When the pin V passes above t e horizontalarrn of the bell crank 43, and in the downward'movement of the said pin, due to the fall-ingot the I said pinwill engage the W of'said bell crankfpushing it,

slide M by gravity, curved part outward and passing below it without otherwise disturbing said bell'crank 431 Secured to a con'vel'iient place on the lower portion of the'slide M is'a bracket V, to which is secured an insulated-plug V Secured to the bottom of the telephone box, and in the path of the plug Vfiare two contact springs 25 and '39, so arranged that the plug V -n1ay enter between them and press them back. In

- their normal positioil the springs 25 and 39 are in contact'with contact points 90 and 23; .but when the plug V enters between the said springs 25 and 39, it 'willpushthemhout of V w-ith respect tothe'springs25 and 39, and

also with respect to the pointer V on 'the front of the slide, and the graduations on the gnidesadjacentthereto,is such that the plug V emerges frombetween the springs 25 and 39 immediately after the pointer Y rises above 'thegraduation marked 0.' The TIC upper hole M in the slide Mis so related to thebell crank 43 and to the movement-of the plugV in-the springs 25 and 39, that immediately upon the emergence of said plug from engagement between the springs 25 and 39, I C in one direction, it attracts the-armature the pin V, if located in the upper hole M which has its north-end adjacent to the pole will engage the bell crank 43 and shift it from) of the relay, and when a current is sent in an, connection with 42 to- 57. These various i opposite direction through the relay, itv at' another subscriber, he first sets the pin 'V 5 )arts are arranged for hundreds and units. tracts the armature which has its south end 7e he pointer V and. the graduations whichl adjacent to the pole of the relay. Connected are adjacent thereto represent hundreds.-

to these two armatures N ands ofthe relay and the holes in the slide represent units; C, are two contact closing. devices, one of For example, the positi-on'shown in Fig. 6 l which is connected to the magnet B of the 10 illustrates the key-board or indicator set for i switch, and the otherof which is connected 75 v 930. That is, the pointer V is set at 9 and i tothe magnet A. It will therefore be a the 'pin V is set at 30. In this position, 1 parent that if a current be sent through t e when the slide Mis movedupward by virtue relay 0 in one direction an electrical connecof rotations'of the generator, nine electrical .tion will be made through which a current contacts will be made between 46 and 45 bemay pass through the magnet B, while if a 0 fore the plug V emerges from between the current be sent through the relayCin the opsprings .25 and. 39, and "following this there 1 posite direction a contact will be made by will-be thirty contacts between 46 and 45bewhich an electrical current may be made to fore the pin v 'engages the bell crank 413, and pass through the magnet A. There is located 2: moves it from contact point 4.2 to contact at a convenient place in the central office a 8 5 point 57. If the slide M be 'moved upward battery X, from one side of which battery a by hand, so that the-pointer V will be adjawire 100 extends with branch connections cent to some other. graduation, then the to the frame C of the magnetC of each switch number of contacts made before the plug V in the exchange. It is to this frame C that p emerges from between-the springs 25'and 39 the armaturesN and S are pivoted, so that 0 will be correspondingly reduced and will be when a current passes to the frame C it may equal to the number indicated on thegradupass through either contact closing device to vation. If the pin V be placed in some other either contact oint 17 or 51 and-thus to hole, than that numberedthirty, the number either magnet or magnet A.. From the 0 of contacts made after the time of the plug other side of the battery X a wire 50'extends 95 V leaving the springs 25 and 39 will be corthrough the exchange with branches to mag respondingly greater or less according to the nets B and A on each switch. The magnet position in which the pin V is placed. D is arranged to operate under a very hght At a convenient place in the front of the current and has its armature D adjusted 3 5 telephone box Lu are two s rings, 28 and '29, very close to the pole of the magnet, and'said 1 *andon the receiver hook C is a pin or proarmature is part of the electrical circuit which jection adapted to engage the spring 29. passes through the magnet D andthrough When the receiver hook is in its elevated po 'the contact point 71. The talking circuit sition these s rings are in electrical conned. passes through the magnet D, but is not 40 tion with eacli other, but when the: hook de.- powerful enough to operate it. If, however, I 5 scends it strikes the spring 29 and breaks any other electric current, as for example a this connection. 1 current from'thegenerator'G, passes through In arranging a telephone exchange, I place the magnet D'it will be sufficiently powerful in a central ofiice a series of switches like that to actuate such magnet and break the con shown in Figs. 1 and 2, and to each switch I nection betweenD and 71, sothat a current I I connectat elephone. The switches are prefassing through the magnet D cannot pass erably located in arow, and near the switches y way ofiD c From contact point 71 the I arrange a bank-ofwires 91, and from each wire extends-to the bar or support H of the pairof wires 91-1 run branchwires to pairs of switch, and fromthe magnet D a wire 32 excontact points on the difierent switches. tends to'a binding post 31on the telephone 11,5 Also next, or adjacent, to each switchl 10-, box of the telephone "which belongs to that cate a relay magnet C and a'second' and articular switch. From the bar or support smaller magnet D. l The magnet, C isar of the switch a wire 34 extends to a bindranged withv two armatures which have their ing-post 35, also on the same tele hone box.

ends polarized, as shown at Nand S, repre From the wire 34 there is a branc to the re- 2 sentin north .and south poles of the mag lay O, and from the relay Cfa' connection 33 netize -.armatures;'.f The relay D is an orto the magnet frame D The various condinary one arranged to operate with avery' tact points in the telephone box, -most of light current and is connected electrically to. which have been described, and allofwhich the generator in the connected telephone.- will be apparent by examining the diagrams 12 5 It is also made with a'suflicient res stance in Figs. 14, 15 and 16, are connected up by to prevent short circuiting thetalking circuit wires in the manner illustrated in said diawhich. passes through lines 34 and 32 as will gram. Y j 5 I be hereinafter explained. When a current Assuming that a subscriber wishes'to call fromthg-generator. is sent throughdhe relay,

into'a hole representing the number of units 1 which are'in the number representing the subscriber, Whom he dcsiresto call. lletlien removes his receiver and adjusts the slide M so that the pointer V is opposite the number of hundrecs of the subscriber whom he wishesto call, He then turns his cranlcCl until the bell rings; 'He then has electrical communication with the subscriber with whom he desires" to talk, and said subscriber hasbeen duly notified. The 6' eration of removing his receiver, setting and turning the crank G are all the opera tionslthat he performs in calling any given .All the otheris indieator,

subscriber in the exchange. operations are automatic, and are as fol lows :'-.Upon turning the crankof hislgenerator said generator isnot in electrical connecf tion with any line except at the moment when thedisk 46 engages the contact spring45. As this point is always at a given portion of the rotation of the generator shaft, acurrent sent from the generator is always in one direction from the armature, and to the line beyond contact spring -15. Upon eachconnection between 46 and45, a current flows from gen-v 37- 38- 39- 40 41- 42-- 43 44---- 45.,46-'20. Thisis a complete circuit in one direction through the relay C, which causes saidrelay to attractthe armature N, I closing connectlonbetween (3 and 47, when a current "flows as' follows:- X7' l00- C 47 48 B 49 50- X. The 0 er'atio-n of the-magnet B rotates the shaft E, ringing the first arm E into contact-with the first rack H and moving said rack into contact with its gear F Each succeeding rotation ofthe generator causes a similar impulse from said generator to be sent through the relay C, which in turn causes a similaropera. t on of the magnet B, moving successive racks to engagement with their respective gears; This operation is continued until the plugV passes out of its engagement ,with the springs and39', after nine, impulses representing hundreds have been sent to central, whensaid springs move into connection with the contact points and 90'. When that occurs, the current then flows 20+- 2l- 22 'trical impulse sent in an opposite direction through the relay 0, which attracts the armature S. making electrical connection with the contactpoint 5], when a current flows follows :'From battery X 100}- This energizes magnet A and rotates the shaft F and, the gears-F so as to move upward the rack H which is in engagement with its gear.

" points in rows of contact points.

slide M has-been moved upward far enough,

, receivers.

This moves thc contact makers P and P up-' ward; step liy .step 'to succeeding contact by repeated rotations. of the generator 20,, so that thirty impulseshave been sent the pin ,V will engage the bell crank 43 and shift it from contact point 42to57, thcnthe current r from the generator is shifted from relay C to "ground through a bell ringing device as fol? lows (Fig. 14) 2()- 21 22- 23- 39- 38.3iT- K-r- 36 35-:- 34 11 P to the selected contact point, -S0T to the bank wire 9.1 and along the connected wire tothe branch-81 (Fig. 16) therefrom, to the barH of the selected switch 34- 35-36 55'56 Q ground at the called telephone to ground at calling telephone- Q- 56-.

5.5" 57 43- 44+ 45-1-46 2o. This operates the ringer of both telephones, 'whieh operation cansesthe arm Q to release thev catches and permit the bell cranks 66 Wheh the K 54- (hook of called switch being down) to. be moved into e ectrical connection with I the contact points 67. The called subscriber removes his receiver when a primar3 circuit is as follows:-Y-. 58'- 59 60-- 61 K 62'Y. The secondary or talking circuit is as follows :-59-- 63- 64,

To release, thesubscribers hang-up their gage thev tail of the pawl M and release it from the rack M? wli ch'permits the said rack and the slide M'to drop again to their nor mal position. The descent of the hook also causes the arm to engage the pin K and 5 At the calling station the descent of the receiver hook causes the rod M to enmove thebell crank'43 from contact point 57 back to its nornial position into engagement with the contact point 142. 'The descent of the receiver hook 1n moving the arm K also vmoves, through the connection (1, the segment of a rack G, which movement causes the generator armature to make two rotations during the time when the hook is de- 74- K 36- 35 34-. C- 33- D D 32 31 75 76- 77- 78 45- 46 20. T1115 current through C attracts the armature his S and makes an electrical circuit from battery ..X through the magnet A precisely as has been previously described. immediately thereafter during the further descent of the hook, and atthe instant when the disk 46 engages the'spring in the second rotation of 'the generator, this previously described current through C is reversed as follows 2Q 21- 22- 2"- 72 73'76 31 32- D-- D 33- c- 34.- :35 36- K 74. 77. 7S- 45* 46 20.. The reversal of the current through the relay C closes the connection of the-.magnet B when a current flows through that magnet from thebattery X has been previously described. This currei'it through magnet A immediately followed by a current through'the magnet B causes the pawl B to. strike the pin E? onthejpawl E and release said pawl from the ratchet wheel E so that 2'0 the spring E may return the arms E to their normal position, which in turn releases the" 'moved rack, and permits it, and the contact I j case a current passes to the'called subscriber makers P and P to drop again to a'normal 1 position. Also in the descent of the re ceiver hook the pin K engages the upper portion 'ofthe bell crank 66, pushing it down- -ward until-said pin passes out of engagement with said arm, which-movement of 'the bell crank causes. it to be moved away fromjcon- ,the catch Q I I It will be-ohserved that'the operations of calling a subscriber are very much simplified and are arranged so that there is a smallchance of error. 'dicator which is set for any required subscriber, and which may be observed by the. calling subscriber beforehe operates his gen .eratcr, the chances of error rising from se 40 lecting numbers during the process of calling is eliminated. As-soon as he hasset'his indicator or key-board and is satisfied that it is at-the right indication, the only operation re-' -.quired of him is to turn the generator crank Guntilthebel] of his generator rings. while turning the crank G} the slide M and the pin V are moving upward directly before his eyes. By reason of the termination of the teeth-of the-ratchet bar M la'lfter the slide is 5.0T moved up acertain distance, which would be equal to the greatest number of indicating" [and B, is entirely confined within the central Y marks on theslidc M. further rotations of the generator will not raise slide and the pin V The upward movement ofthe said. :sl'ide does not'stop atthe instant that the proper con-. nection is made to the required telephone but proceeds upward until'the end of the ratchet M is reached or until the subscriberstops turning the crank G The bell, ho'w 6o ever, begins to ring the instant the proper 7 connection is made to, the required subscriber because, upon that connectiorrbeing made,

the pin V moves the bell (rank 43 from conerator, and also arranging the-generator so nection to its switch mechanism to connec'- 5/ tion with the bell rmgmg device, so that the tact point 67 and to be engaged and held by By using a key-boarder ili- I .bell rings immediately. From this it will be apparent that if the subscriber, in turning his crank, observes that his indicating slide M no. longer advances upward and the bell has not rung at the time when it stops, it will indicate to the calling subscriber that the one to whom he wishes to talk is busy. The reason for thebellnet ringing is as follows: It will be observedby the diagram that a current passing to the bell ringer Q must go by contact pcirit 54 through the hook K,.or by contact point 57 through the .bell crank 43. At the calling telephone the subscriber has removed. his receiver, so that the connection between K and 54 is broken. He therefore can reach the bell ringing device only when the bell crank 43 is moved to 57, which, as has been previously shown, occurs when the pin V reaches the said bell crank. In. the called telephone the'bell crank 43 is not moved, but the subscribers receiver hook is down in its normal position if is not busy, 'in which through the receiver hook. From this it will beseen that the instant a called subscriber removes his receiver, he can no longer be reachedthrough the bell ringing device. .'As'. the bell ringingdevices cf'the called and calling, subscribers are in oneand thcsame cirscriber cannotri'ng the bell ringing device, of the one to whomhe wishes toconverse, it -will be evident that he cannot ring his own. It will also be apparent that the talking circult is at all times between the contact points 67 and the bell crank 66, that thisconnectior isnormally disengaged until operated or re leased by the bell ringer. From this it will be apparent that as the calling subscriber cannot operate his bell ringer when he moves his switch to a telephone that is busy, that this inability to operate'his ringer prevents hirnfrom completing-the talking circuit at his own telephone between 66 and '67. bell crank 66 and contact point 67, together with the ringer Q, form what .maybe called a noi'i-interl'ering device, which in this case, is purely mechanical, operated or brought into operation by an electrical device. The operating circuit, which is the circuit that passes throughthe operating magnets A oflice and the currents therethrough do not consist of electrical impulses sent'from dis- 1 ta n't sub-stations. In ordinary auwmsus usually necessary; or atleast advisable, to use copper wires betw en the telephones and the centralfstation,-whichin long lines, means a considerable expense. By using a relay .which may be. operated by a "very light current and then connecting said relay to a. genthat the direction of" current Wlll be as re cuit, it'will beevident that it the calling sub- 9 The telephone exchanges, when the battery -circult has passed over long d1stances," 1t 1s quired,-I produce an arrangement by which the wires from the central ollice to the local stations may be made of iron instead of copper. cuits through the magnctsA and B to the exchange, not permitting them at any timeto connect to or pass over the lines connecting the central o'llice with its local stations, I avold the possllnhty of ever havm a very heavy battery current pass-to a tal mg circuit. By arranging the contact makers in pairs and by connectin the pairs of contact points by pairs of ban wires, and pairs of connections to the telephones, I' am enabledto produce an entire and complete metallic circuit between two telephones, which does,

a not at any time pass to ground or in any way connectwith any line or branch which at any time is art of some-other talking circuit.

It wil be obscrvedin tracing the talking a circuit described, that there is'a complete-me tallic circuit between the two telephones which are in telephonic communication and that this talking circuit has no branch or con nection at any place to the operating circuit consisting of the battery X and the lines 50 and 100. It will also be observed that no part of the circuit at any point passes over a number of contacts made for an no which is or can be a common talking circuit between any other two telephones, as is ordinarily'the case in telephoneexchanges as heretofore made.

The arran 'ement of numbers on the keyboard or indicator, as illustrated in Fi 1,-i s

made for hundreds and any number 0 units up to 99, if desired. It is not necessary, how-1 ever, that the division between units and hun dreds be inthis particular form. For example if the limit numberof the telephones in the exchange is625, there may be six graduations for hundreds and ninety-nine graduations for the units, in which case the greatest selection would be six plus ninety-nine, W ich is' 105 contacts as the great-est number. There might, however, be ten graduatlons for the hundreds and sixty' three graduations in the units, in which case there would be, as the greatest number of contacts made ten plus sixty-three, equal seventy-three contacts. By making twenty-five graduations in the hundred and twent -five graduations in the units, there would be also' a. combination of 625 telephones; but the greatest number of contactshnade would be twenty-five plus twenty-five, equal fifty. It will be under-- stood that the number of-graduations indi cated by the hundred marks at the lower portion of the indicator represent the number of racks Hior pairs-of contact makers P and]? and that'the number of graduations on the slide represent the number of pairs of contact points in one ofthe verticalipairs of rows of contact points marked T in Fig. 1.

Also by confining the operating c1r- What I claim is? 1. The combination with a switching mechanism, and two magnets for operating it, of a relay and electrical connections for closing an electric circuit through either magnet according to the direction in which electrical impulses'flow through said relay, 8. generator provided with a crank by the turning of which electrical impulses are sent through said relay, and automatically operating means for reversing the direction of the current when a predetermined number of impulses have been sent in one direction.

, 2.. In a telephone exchange, the combinetion with electrically operated devices and two magnets therefor, of a relay adapted to close a circuit for either magnet according to' the direction in which impulses flow through said relay, a generator provided with means.

by which electrical impulses are sent through said relay, and automatically I operating means for reversing the. d1rect1on of the ourrent when a predetermined number of im pulses have been sent in one direction.

3. The combination with electrically operated devices and two magnets therefor, of a relay adapted to close a circuit for either provided with means by which electrical impulses are sent through said relay, and automagnet according to the direction in which impulses flow throughsaid relay, a generator matically o crating means for reversing the direction 0 the current when a predetermined number of impulses have been sent in one direction and for stopping the impulses through the relay when a predetermined number of impulses have been sent in the re-,

versed direction 4. The combination with a switchlng 'mechanism and electrical devices for operat ing it, of a relay for controlling such operamatically operating means for dividing the two series in any desired proportion and extent from a larger and continuous series.

5. The combination with a switching mechanism and two magnets for operating it,

of a relay and electrical connections for closnet according to the direction in which electrical impulses flow through said relay, a generatpr and connections-for sending impulses through said relay, a crank for operating said generator, ainadiustable indicator for controlling the im'pu ses sentbysaid generator, and means foroperatingsa-id indicator by the movement of sald generator.

6 The combination with a switching tion, a generator, means for sending from saidgenerator a series of electrical impulses in one direction and a second series 'in an ()1)?- posite direction through said relay,-and auto- .ing an electrical circuit through either magmechanism and magnets foroperating it, of

a generator and connections for sending electrical impulses for controlling said 1nagnets,a 

